Sensor module

Abstract

A sensor module (100) that is attached to an opening part (2) of a container (1) in which contents (5) are accommodated comprises a cap (3) and a sensor part (20). The cap (3) has a lid part (3a) that closes the opening part (2), a lens part (32), a support wall (33) that is positioned standing upright around the lens part (32) and supports the sensor part (20), and a side wall (36). The sensor part (20) has a transmission / reception part (21) that includes a transmission part (21a) and a reception part (21b). The lens part (32) is positioned so as to face the transmission / reception part (21) of the sensor part (20), the transmission part (21a) transmits radio waves that pass through the lens part (32) and reach an internal space (1a) of the container (1), and after the radio waves are reflected by the contents (5) in the internal space (1a), the reception part (21b) receives the reflected waves. The side wall (36) is positioned standing upright, in the same direction as the support wall (33), around the lens part (32).

Description

Sensor Module

[0001] The present disclosure relates to a sensor module.

[0002] For example, in cold regions such as Hokkaido, kerosene is used as the primary fuel for heating appliances in buildings. To ensure continuous use of heating appliances in winter, fuel tanks are often installed outdoors as a kerosene supply source for the heaters, allowing for the supply of kerosene from outdoors to indoor heaters. However, to ensure continuous use of the heaters, it is desirable to refill the kerosene in the fuel tank before it runs out, rather than waiting until it runs out. For this reason, some fuel tanks are equipped with a dedicated remaining fuel level sensor.

[0003] Patent Literature 1 discloses a radar water level measurement device using a radar signal. This radar water level measurement device has an antenna unit that emits a radar signal toward a water level boundary surface and receives the radar signal reflected from the water level boundary surface, and a control unit that performs transmission control for the radar signal emitted by the antenna unit, reception control for the radar signal received by the antenna unit, and water level measurement control using the received radar signal. The antenna unit has a lens for transmitting and receiving the radar signal in a direction perpendicular to the water level boundary surface, and an absorber for reducing side lobes of the radar signal transmitted and received through the lens.

[0004] Japanese Patent Application Laid-Open No. 2022-079404

[0005] The radar water level measurement device described in Patent Document 1 can use an absorber to reduce the side lobes of the radar signal transmitted from the radar signal transmission / reception processor in the direction of the waveguide and lens, but cannot use an absorber to reduce the side lobes of the radar signal transmitted in other directions. Furthermore, this radar water level measurement device uses a separate component called the waveguide, which increases the number of components in the device, increases the assembly man-hours, and may result in increased costs.

[0006] Therefore, there is a demand for a sensor module that is low cost and can reduce the side lobes of radio waves that adversely affect the accuracy of detecting the remaining amount.

[0007] One embodiment of a sensor module according to the present disclosure is a sensor module attached to the opening of a container that holds an item, and comprises a cap and a sensor unit, wherein the cap has a lid portion that closes the opening, a lens portion, a support wall that is arranged upright around the lens portion and supports the sensor unit, and a side wall, the sensor unit has a transceiver portion that includes a transmitter portion that transmits radio waves and a receiver portion that receives the radio waves, the lens portion is arranged opposite the transmitter portion of the sensor unit, the transmitter portion transmits the radio waves that pass through the lens portion and reach the internal space of the container, and the receiver portion receives the reflected waves after the radio waves are reflected by the item in the internal space, and the side wall is arranged upright around the lens portion in the same direction as the support wall.

[0008] According to this embodiment, the sensor module is disposed at the opening of the container, eliminating the need to modify an existing container to accommodate the sensor module. The remaining amount of content stored in the container can be detected without modification. Furthermore, since the remaining amount of content is calculated using radio waves, the remaining amount of content can be easily detected at a set time interval. Furthermore, since a sidewall is disposed between the lens unit and the support wall disposed upright around the lens unit and extending in the same direction as the support wall, adverse effects of side lobes of radio waves transmitted from the transmitter on reflected waves can be suppressed. By providing the sidewall as a separate part from the support wall, the position of the sidewall can be freely set depending on the sidelobe generation conditions. Because the support wall is required to support and secure the sensor unit, there may be restrictions on the position and shape of the sidewall when it is disposed on the support wall.

[0009] In another embodiment of the sensor module according to the present disclosure, the sensor unit further has a calculation unit that calculates the remaining amount of the contained item or information for calculating the remaining amount based on the time from when the radio wave is transmitted from the transmitter unit to when the reflected wave is received by the receiver unit.

[0010] According to this embodiment, the calculation unit calculates the remaining amount or information for calculating the remaining amount of the contained items by calculating the time it takes for radio waves to be reflected directly off the contained items and received, so that a single sensor module can detect the remaining amount or information for calculating the remaining amount with high resolution.

[0011] Another embodiment of the sensor module according to the present disclosure further includes an external communication unit, which wirelessly transmits to the outside a signal indicating the remaining amount of the contained item calculated by the calculation unit or information for calculating the remaining amount.

[0012] According to this embodiment, the sensor module can know the remaining amount of the contents at a location away from the container without having to visually check the inside of the container.

[0013] Another embodiment of the sensor module according to the present disclosure further includes a power supply unit, which supplies power to the sensor unit and the external communication unit.

[0014] According to this embodiment, the sensor module can continue to operate without using an external power source.

[0015] Another embodiment of the sensor module according to the present disclosure further includes a housing configured to be detachable from the cap, and the sensor unit is housed in a closed space formed by the cap and the housing.

[0016] According to this embodiment, the cap and the housing are detachable, so that, for example, when the sensor unit breaks down, the housing can be removed from the cap, and the sensor unit can be repaired or replaced.

[0017] In another embodiment of the sensor module according to the present disclosure, the side wall is integrally formed with the lid portion.

[0018] According to this embodiment, the cap can be manufactured with fewer steps and at lower cost than when the lid portion and the side wall are manufactured separately and then assembled. Also, a cap with high positional accuracy of the side wall relative to the lid portion can be obtained.

[0019] In another embodiment of the sensor module according to the present disclosure, the side wall has a cylindrical shape.

[0020] According to this embodiment, it is possible to reduce the side lobes that adversely affect the reflected waves, regardless of the direction in which the side lobes of the radio waves are transmitted from the transmitter. Furthermore, restrictions on the mounting direction of the transmitter / receiver are eliminated, increasing the degree of freedom in assembling the sensor module.

[0021] In another embodiment of the sensor module according to the present disclosure, the radio waves transmitted from the transmitter are millimeter waves.

[0022] According to this embodiment, by using millimeter waves as radio waves, the radio waves can penetrate resin. Therefore, even if the sensor module is placed on the outside of a resin cap of a container, the remaining amount of contents in the container can be calculated through the cap. If the radio waves were light such as infrared or visible light, the cap would need to be partially or entirely made of transparent or translucent resin or holes would need to be drilled in order for the radio waves to pass through the cap. However, by using millimeter waves as radio waves, it is not necessary to use a transparent or translucent material for the cap or to drill holes.

[0023] FIG. 1 is an exploded view showing a state in which the sensor module according to the present embodiment is separated from the fuel tank; FIG. 2 is an exploded perspective view of the sensor module; FIG. 3 is an exploded perspective view of the sensor module; FIG. 4 is a cross-sectional view showing the sensor module attached to the fuel tank; FIG. 5 is a diagram showing the results of an electromagnetic field simulation of radio waves transmitted from a transmitter when there is no side wall; and FIG. 6 is a diagram showing the results of an electromagnetic field simulation of radio waves transmitted from a transmitter when there is a side wall.

[0024] Hereinafter, embodiments of a sensor module according to the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are examples for explaining the sensor module, and the sensor module according to the present disclosure is not limited to these embodiments. Therefore, the sensor module according to the present disclosure can be embodied in various forms without departing from the spirit of the present disclosure.

[0025] [Configuration of the Sensor Module] As shown in FIG. 1 , the sensor module 100 according to this embodiment is attached to the outside of an opening 2 of a fuel tank 1 (an example of a container). The fuel tank 1 includes a tank body 1b and a cylindrical opening 2 protruding from the tank body 1b. The internal space 1a of the tank body 1b is connected to the interior space of the opening 2, and kerosene 5 (an example of a stored content) is poured through the opening 2 and supplied to the internal space 1a. As a result, the kerosene 5 is stored in the internal space 1a. The sensor module 100 detects the remaining amount of kerosene 5 stored in the internal space 1a of the fuel tank 1 or information for calculating the remaining amount (hereinafter, referred to as "remaining amount, etc."). The cap 3 is made of resin and is screwed onto the opening 2 to close the opening 2. Note that the engagement between the cap 3 and the opening 2 can be achieved by any method, not limited to screwing.

[0026] As shown in FIGS. 2 to 4, the sensor module 100 includes a cap 3, a housing 10, a sensor unit 20, a power supply unit 60, and an external communication IC 90 (an example of an external communication unit).

[0027] The sensor unit 20 is configured to include a transmitting / receiving IC 21 (an example of a transmitting / receiving unit) and a calculation IC 22 (an example of a calculation unit). As shown in Figures 2 and 3, the transmitting / receiving IC 21 and the calculation IC 22 are mounted on different surfaces of the first substrate 40. The transmitting / receiving IC 21 has a transmitting unit 21a and a receiving unit 21b. Note that the transmitting / receiving IC 21 and the calculation IC 22 may be mounted on the same surface of the first substrate 40.

[0028] The transmitter 21a of the transmitter / receiver IC 21 has a function of modulating a signal to be transmitted and transmitting the modulated signal to the outside, and the receiver 21b has a function of demodulating the radio waves from the outside and receiving the signal. The transmitter / receiver IC 21 can receive the radio waves transmitted from the transmitter 21a at the receiver 21b. The transmitter / receiver IC 21 mounted on the first board 40 modulates the signal to be transmitted and transmits the radio waves from a transmitting antenna (not shown) of the transmitter 21a, and demodulates the radio waves received from a receiving antenna (not shown) of the receiver 21b. The calculation IC 22 has a function of calculating the remaining amount of kerosene 5 stored in the internal space 1a of the fuel tank 1, etc., based on the time it takes for the radio waves transmitted from the transmitting antenna to be received by the receiving antenna.

[0029] The power supply unit 60 includes a power supply IC 61 and a battery unit 62. The power supply IC 61 is mounted on the same surface of the first substrate 40 as the arithmetic IC 22. The battery unit 62 includes a battery 62a and a battery socket 62b that holds the battery 62a. The battery socket 62b holding the battery 62a is mounted on the surface of the second substrate 50. The transmitter / receiver IC 21, arithmetic IC 22, power supply IC 61, and external communication IC 90 mounted on the first substrate 40 operate by receiving power from the battery 62a mounted on the second substrate 50. The battery unit 62 may be a secondary battery or a combination of a self-power-generating device and a secondary battery. The power supply IC 61 may be mounted on a surface of the first substrate 40 different from the surface on which the arithmetic IC 22 is mounted. Furthermore, if the sensor module 100 does not include the second substrate 50, the battery unit 62 may be configured to be mounted on the first substrate 40.

[0030] The external communication IC 90 is mounted on the same surface of the second substrate 50 on which the battery unit 62 is mounted. An external communication antenna 91 that transmits a signal generated by the external communication IC 90 to the outside is formed as a pattern on the same surface of the second substrate 50 on which the external communication IC 90 is mounted. The external communication antenna 91 may be configured using a dedicated antenna component instead of a pattern, or may be built into the external communication IC 90. Furthermore, if the sensor module 100 does not include the second substrate 50, the external communication IC 90 may be configured to be mounted on the first substrate 40.

[0031] As shown in FIGS. 2 and 4 , the first substrate 40 and the second substrate 50 are electrically connected by a connecting member 80. The connecting member 80 may be any member that electrically connects the first substrate 40 and the second substrate 50, such as a flexible flat cable (FFC) or a flexible printed circuit (FPC). In this case, connectors 82, to which both ends of the connecting member 80 are electrically connected, are mounted on the first substrate 40 and the second substrate 50. That is, the first substrate 40 and the second substrate 50 are electrically connected by the connector 82 mounted on the first substrate 40, the connecting member 80, and the connector 82 mounted on the second substrate 50. Instead of the above configuration, the first substrate 40 and the second substrate 50 may be electrically connected by a harness including electric wires and plugs and receptacles mounted on each of the first substrate 40 and the second substrate 50, or may be configured as a board-to-board connector, or may have other configurations.

[0032] 1 to 4 , the sensor unit 20 including the first substrate 40, the calculation IC 22, and the power supply IC 61, the battery unit 62 including the second substrate 50 and the external communication IC 90, and the connecting member 80 and connectors 82, 82 will be referred to as a sensor assembly 70. In other words, the sensor assembly 70 is a general term for an assembly including the sensor unit 20, the power supply unit 60, the external communication IC 90, and the first substrate 40 and the second substrate 50 that are mounted thereon and electrically connected by the connecting member 80. In other words, the sensor module 100 is configured to include the cap 3, the housing 10, and the sensor assembly 70.

[0033] The cap 3 is configured to have a lid portion 3a, a fixed portion 3b, a lens portion 32, a support wall 33, and a side wall 36. The cap 3 is made of resin, and the lid portion 3a, the fixed portion 3b, the lens portion 32, the support wall 33, and the side wall 36 may each be molded separately, or at least two of them may be integrally formed. When integrally formed, specifically, the cap 3 is formed by supplying molten resin to a single molding die and curing it.

[0034] The lid portion 3a has a cylindrical shape with a bottom, and a female thread is formed on its inner surface (see FIGS. 3 and 4). The female thread is threadedly engaged with a male thread (see FIGS. 1 and 4) formed on the outer surface of the opening 2 of the fuel tank 1, thereby fixing the cap 3 to the fuel tank 1. The method of fixing the cap 3 to the fuel tank 1 is not limited to threading the lid portion 3a to the opening 2, and other methods may be used. A lens portion 32, a support wall 33, and a side wall 36 are formed on the bottom wall 31 of the lid portion 3a. The support wall 33 is formed to stand upright from the fixing portion 3b toward the side opposite to the side where the opening 2 is located.

[0035] The fixing portion 3b extends radially outward from the side surface of the cover portion 3a. The outer edge of the fixing portion 3b forms a first peripheral wall 3d that stands upright in the radial direction, and a female thread 3e is formed on the inner peripheral surface of the first peripheral wall 3d.

[0036] The lens unit 32 extends from the bottom wall 31 of the cover 3a and faces the transceiver IC 21 of the sensor unit 20. In this embodiment, the transceiver IC 21 and the top surface 32a of the lens unit 32 are in close contact with each other. However, the transceiver IC 21 and the top surface 32a of the lens unit 32 may be spaced apart. The lens unit 32 exhibits its lens function by varying its thickness and shape. The inclusion of the lens unit 32 in the cap 3 improves the efficiency of transmission and reception of radio waves from the transceiver IC 21. Specifically, the lens unit 32 is formed by stacking multiple (e.g., three) cylinders whose outer diameters decrease from the bottom wall 31 toward the transceiver IC 21. In this embodiment, the lens unit 32 has a convex lens shape. However, it may also have a concave lens shape, or it may extend in an opposite direction from the bottom wall 31, or it may extend in both directions. Any lens shape can be used depending on the purpose. Furthermore, the lens unit 32 does not necessarily have a lens function. The bottom wall 31 of the lid portion 3 a that is integrally formed with the lens portion 32 may function as a part of the lens portion 32 .

[0037] The support wall 33 is disposed around the lens portion 32 and has a cylindrical shape erected from the outer edge of the bottom wall 31. A plurality of (four in this embodiment) support bosses 34 extending along the erection direction of the support wall 33 are integrally formed at the tip of the support wall 33 and are evenly spaced around the circumference of the support wall 33. The first substrate 40 and the second substrate 50 are supported by the support bosses 34 and thereby fixed to the cap 3. Through holes are formed in the first substrate 40 and the second substrate 50 at locations corresponding to the support bosses 34, and the support bosses 34 pass through the through holes. The number of support bosses 34 does not have to be multiple, and a single support boss 34 may be used. The support bosses 34 may be positioned on the support wall 33 by press-fitting, adhesive bonding, or other methods. The support bosses 34 may be unevenly spaced around the circumference of the support wall 33.

[0038] In this embodiment, the first substrate 40 is fixed to the cap 3 by the support boss 34 so that the transceiver IC 21 abuts against the top surface 32a of the lens portion 32. That is, the lens portion 32 is raised to a height sufficient to allow the transceiver IC 21 to abut against the top surface 32a when the first substrate 40 is fixed to the cap 3. The first substrate 40 and the second substrate 50 may be fixed to the cap 3 by the support boss 34, for example, by heating and melting the tip of the support boss 34 and thermally welding it to the second substrate 50. Alternatively, the tip of the support boss 34 may be shaped like a split pin to fix the first substrate 40 and the second substrate 50. Alternatively, a female thread may be formed at the tip of the support boss 34 and fixed with a male screw, or the support boss 34 may be omitted and the substrate may be fixed to the support wall 33 with a male screw. Any method may be used as long as it can fix the first substrate 40 and the second substrate 50 to the cap 3.

[0039] When the first substrate 40 and the second substrate 50 are supported by the support bosses 34, a spacer 42 is disposed between the first substrate 40 and the second substrate 50 and inserted through the support bosses 34. The spacer 42 separates the first substrate 40 and the second substrate 50 by the length of the spacer 42. Alternatively, instead of the above configuration, the outer diameter of the support boss 34 may be larger at the base end and smaller at the tip end, providing a step between the base end and the tip end. The first substrate 40 may be formed with a through-hole having an inner diameter that allows the base end of the support boss 34 to be inserted therethrough, and the second substrate 50 may be formed with an inner diameter that allows the tip end of the support boss 34 to be inserted therethrough but not the base end. As a result, when the first substrate 40 and the second substrate 50 are inserted into the support bosses 34, the second substrate 50 is supported by the step between the base end and the tip end of the support boss 34, so that the first substrate 40 and the second substrate 50 are fixed in a spaced-apart state even without the spacer 42. The first substrate 40 and the second substrate 50 may be arranged by separate support bosses 34 having different outer diameters. In this case, the spacer 42 is also unnecessary.

[0040] When the sensor module 100 includes the second substrate 50, the first substrate 40 and the second substrate 50 can be fixed to the cap 3 using at least one support boss 34 and a spacer 42 for maintaining a constant distance between the opposing plate surfaces of the first substrate 40 and the second substrate 50 (see FIG. 4 ). Alternatively, the first substrate 40 may be fixed to the cap 3 using at least one support boss 34, and the second substrate 50 may be fixed to the cap 3 using other support bosses (not shown). Furthermore, both the first substrate 40 and the second substrate 50 may be fixed to the cap 3 by other methods. The phrase "fixed to the cap 3" includes both direct fixation to the cap 3 and indirect fixation to the cap 3 via other members. The support boss 34 and / or other support bosses may be integrally formed with the cap 3, integrally formed with the lens unit 32, or separate.

[0041] The transmitting / receiving IC 21 (which has a transmitting antenna and a receiving antenna, not shown) mounted on the first substrate 40 is covered by the support wall 33. Here, being covered by the support wall 33 means that the support wall 33 and the first substrate 40 abut against each other and the transmitting / receiving IC 21 is completely housed inside the support wall 33, as shown in FIG. 4 . However, this does not necessarily mean that the supporting wall 33 and the first substrate 40 are in contact with each other, and it also includes the case where there is a gap between the supporting wall 33 and the first substrate 40. In this case, at least a portion of the transmitting / receiving IC 21, the transmitting antenna, not shown, and the receiving antenna, not shown, are visible through the gap between the supporting wall 33 and the first substrate 40.

[0042] The sidewall 36 is disposed between the lens portion 32 and the support wall 33 and has a cylindrical shape. That is, the sidewall 36 is disposed radially outward of the lens portion 32 and radially inward of the support wall 33. That is, the sidewall 36 stands upright around the lens portion 32 in the same direction as the support wall 33. The sidewall 36 stands upright so as to protrude from the bottom wall 31 toward the transceiver IC 21. In this embodiment, the protruding end 36a of the sidewall 36 is in contact with or located near the first substrate 40 (see FIG. 4). As a result, the sidewall 36 almost completely overlaps the transceiver IC 21 when viewed radially. That is, almost the entire transceiver IC 21 is located in the radially inner space 36b of the sidewall 36.

[0043] The housing 10 is made of resin or metal and has a cylindrical shape with a bottom, the inner diameter of which is larger than the outer diameter of the lid portion 3a of the cap 3. A male thread 10b is formed on the outer peripheral surface of the second peripheral wall 10a of the housing 10. When the sensor assembly 70 is fixed to the cap 3, the male thread 10b of the housing 10 is threadedly engaged with the female thread 3e of the cap 3. An annular seal 15 is disposed at the boundary between the second peripheral wall 10a of the housing 10 and the first peripheral wall 3d of the fixing portion 3b of the cap 3 (see FIG. 4 ). This seal 15 closes the first space 11 (an example of a closed space) that houses the sensor assembly 70, maintaining it in a watertight state. The engagement between the housing 10 and the cap 3 is not limited to threaded engagement, and any appropriate method, such as screw fastening, snap fitting, welding, or adhesive, can be used.

[0044] The effect of engagement using a screw other than threaded engagement, snap fit, welding, adhesive, etc. is that when opening the opening 2 of the tank body 1b, the fastening of the lid 3a to the opening 2 is loosened, but this prevents the cap 3 from being accidentally loosened from the housing 10. This makes it possible to remove the housing 10 more easily than the cap 3, preventing dust, water droplets, foreign matter, etc. from entering the interior.

[0045] Furthermore, the effect of screw fixation and snap fit is that the housing 10 and cap 3 can be detached, just like with screwing, so that when the sensor unit 20 malfunctions or when the battery 62a of the power supply unit 60 needs to be replaced, the housing 10 can be removed from the cap 3, and the sensor unit 20 can be repaired or replaced or the battery 62a can be replaced, etc.

[0046] Furthermore, when fastening with screws, the use of an O-ring or the like can improve the waterproofing effect of the first space 11 through the fastening force and compression force of the screw. Furthermore, by using a structure in which screws are inserted and tightened from the cap 3 side into the housing 10 side, and locking and fixing the lid portion 3a of the sensor module 100 to the opening 2 of the tank body 1b in a fastened state, the screws used to fasten the housing 10 to the cap 3 are hidden, making it difficult to easily remove the screws. Since the housing 10 cannot be easily detached from the cap 3, it is possible to prevent tampering by removing the housing 10. As a method of locking and fixing, for example, when the lid portion 3a is tightened as tightly as possible to the opening 2 of the tank body 1b, overlapping rings can be provided on both the sensor module 100 side and the fuel tank 1 side, and the holes in the rings can be used to lock and fix the lid portion 3a to the opening 2 of the tank body 1b.

[0047] The female thread 3e of the fixing portion 3b of the cap 3 and the male thread 10b of the second peripheral wall 10a of the housing 10 may be reversed. Specifically, a male thread is formed on the outer circumferential surface of the first peripheral wall 3d of the fixing portion 3b, and a female thread is formed on the second peripheral wall 10a of the housing 10, and the male thread and the female thread are screwed together. In this case, an annular seal 15 is disposed at the boundary between the second peripheral wall 10a of the housing 10 and the first peripheral wall 3d of the fixing portion 3b. Even with this structure, the first space 11, which is closed by the cap 3 and the housing 10 and houses the sensor assembly 70, can be maintained in a watertight state. The seal 15 for maintaining the watertight state may be an O-ring, a caulking agent, a water-repellent material applied to the threaded portion, or another method. Note that the seal 15 is not shown in FIGS. 2 and 3 .

[0048] [Operation of Sensor Module] Next, detection of the remaining amount of kerosene 5 using the sensor module 100 will be described with reference to Figure 4. The sensor module 100, which is arranged outside the fuel tank 1, modulates a transmission pulse signal generated by the transceiver IC 21 mounted on the first board 40 at predetermined time intervals (e.g., every 10 minutes) and transmits the modulated signal as radio waves from a transmitting antenna (not shown) of the transceiver IC 21 toward the interior space 1a of the fuel tank 1. The transmitting antenna transmits millimeter-wave radio waves that pass through the resin lens portion 32 formed on the cap 3 and are reflected by the kerosene 5. The radio waves are, for example, electromagnetic pulses.

[0049] The radio waves transmitted from the transmitting antenna and entering the internal space 1a of the fuel tank 1 are reflected by the liquid surface 5a of the kerosene 5, and travel as reflected waves toward the sensor module 100. The reflected waves pass through the cap 3 and the lens portion 32 and are received by a receiving antenna (not shown).

[0050] When radio waves are transmitted from the transmitting antenna, it is ideal that all of the transmitted radio waves are directed toward the internal space 1a of the fuel tank 1, but some of the radio waves may be transmitted to the side, i.e., in the direction of the support wall 33, rather than toward the internal space 1a. Hereinafter, the radio waves transmitted in the direction toward the internal space 1a will also be referred to as the main lobe, and the radio waves transmitted in directions other than the direction toward the internal space 1a will also be referred to as the side lobe.

[0051] If the radio waves transmitted from the transmitting antenna have not only a main lobe but also side lobes, the side lobes may have a negative effect when the radio waves reflected by the surface of the kerosene 5 stored in the fuel tank 1 are received by the receiving antenna, potentially reducing the accuracy of detecting the remaining amount of kerosene 5, etc. However, in this embodiment, a cylindrical side wall 36 is formed around the lens portion 32 of the cap 3. Therefore, dielectric loss, reflection, refraction, etc. occur in the side wall 36 for the side lobes radiated laterally from the transmitting antenna, and the side lobes that pass through the side wall 36 are reduced. This reduces the side lobes that negatively affect the reflected waves, making it possible to suppress a reduction in the accuracy of detecting the remaining amount of kerosene 5, etc.

[0052] The reflected wave (electromagnetic pulse) received by the receiving antenna is demodulated into a received pulse signal, which is then input to the calculation IC 22. The calculation IC 22 measures the time from when the electromagnetic pulse is transmitted from the transmitting antenna until the reflected wave is received by the receiving antenna (hereinafter also referred to as the propagation time), and calculates the remaining amount of kerosene 5 in the internal space 1a of the fuel tank 1 based on the propagation time. The calculation IC 22 previously stores the propagation time when kerosene 5 is sufficiently stored in the internal space 1a of the fuel tank 1 up to its upper limit amount (hereinafter also referred to as the full amount) (hereinafter also referred to as the full amount propagation time), and calculates the remaining amount of kerosene 5 from the ratio or difference between the full amount propagation time and the propagation time. The calculation of the remaining amount, etc. may be configured to store the propagation time when the kerosene 5 is empty or 50% full, and calculate the remaining amount, etc. based on this, regardless of the comparison with the full amount propagation time.

[0053] The calculation IC 22 calculates the distance to the liquid level 5a to calculate the remaining amount of kerosene 5 in the fuel tank 1, for example, every 10 minutes, and outputs a signal indicating the remaining amount of kerosene 5 when the remaining amount falls below 50% of the full amount (hereinafter also referred to as below a predetermined amount). The signal output from the calculation IC 22 is input to the external communication IC 90 via the connection member 80. When the external communication IC 90 receives a signal indicating the remaining amount of kerosene 5 from the calculation IC 22, it transmits a wireless signal from the external communication antenna 91 to the outside of the sensor module 100, the wireless signal including the remaining amount of kerosene 5 and a unique number identifying the fuel tank 1. A fuel retailer or management company that receives the wireless signal determines the remaining amount of kerosene 5 in the fuel tank 1. If the received wireless signal is information for calculating the remaining amount, the remaining amount of kerosene 5 can be determined by calculating the remaining amount of kerosene 5 using a system (not shown) of the fuel retailer or management company based on this information. In addition, the signal output from the calculation IC 22 or the wireless signal transmitted from the external communication IC 90 may not be the remaining amount of kerosene 5, but may be the ratio of the remaining amount to the full amount of kerosene 5, etc.

[0054] In this way, by using the sensor module 100 in the fuel tank 1, a fuel dealer or management company can grasp the remaining amount of kerosene 5 every 10 minutes by receiving a wireless signal transmitted from the external communication antenna 91 at the store or company when the kerosene 5 in the fuel tank 1 falls below a predetermined amount. This eliminates the need for the fuel dealer or management company to visit the installation location of the fuel tank 1 and measure the remaining amount of kerosene 5. When the fuel dealer or management company determines that the remaining amount of kerosene 5 in the fuel tank 1 is below a predetermined amount, the fuel dealer or management company can appropriately refill the fuel tank 1 with kerosene 5. Furthermore, since the owner of the fuel tank 1 can grasp the remaining amount of kerosene 5 every 10 minutes by receiving the wireless signal transmitted from the external communication antenna 91 at home, the owner can request a fuel dealer or management company to refill the kerosene 5 when the remaining amount of kerosene 5 in the fuel tank 1 falls below a predetermined amount.

[0055] Effect of the Sensor Module In the sensor module 100 of this embodiment, a side wall 36 is disposed around the lens portion 32 of the cap 3. Therefore, dielectric loss, reflection, refraction, etc. occur at the side wall 36 for the side lobes radiated laterally from the transmitting antenna, and the side lobes that pass through the side wall 36 are reduced. This reduces the side lobes that adversely affect the reflected waves reflected by the liquid surface 5a of the kerosene 5, making it possible to suppress a decrease in the accuracy of detecting the remaining amount of kerosene 5, etc.

[0056] Fig. 5 shows the results of an electromagnetic field simulation of radio waves transmitted from the transmitting antenna of the transmitter 21a when the side wall 36 is not present. Fig. 6 shows the results of an electromagnetic field simulation of radio waves transmitted from the transmitting antenna of the transmitter 21a when the side wall 36 is present. In Figs. 5 and 6, the darker the color shown, the stronger the electromagnetic field strength, and the area surrounded by an ellipse indicates the strength of the electromagnetic field of the side lobe. From Figs. 5 and 6, it can be seen that the side lobe is reduced when the side wall 36 is present compared to when the side wall 36 is not present.

[0057] According to the sensor module 100 of this embodiment, the sensor module 100 is disposed outside the fuel tank 1, so there is no need to modify the fuel tank 1 in order to dispose the sensor module 100 in an existing fuel tank 1, and the remaining amount of kerosene 5 contained in the fuel tank 1 can be calculated as is. Also, because the remaining amount of kerosene 5 is calculated using radio waves, the remaining amount of kerosene 5 can be easily detected (calculated) at set time intervals. Furthermore, because the remaining amount of kerosene 5 is calculated by directly reflecting radio waves off the kerosene 5 and calculating the time until the radio waves are received, the remaining amount of kerosene 5 can be detected with high resolution using a single sensor module 100.

[0058] In the cap 3 of the sensor module 100 of this embodiment, the lid portion 3a, fixing portion 3b, lens portion 32, support wall 33, and side wall 36 are integrally formed by supplying molten resin to a molding die and hardening it, so the cap 3 can be manufactured with fewer steps and at lower cost than if these were manufactured and assembled separately. Also, the cap 3 can be obtained with high positional accuracy of the lid portion 3a, fixing portion 3b, lens portion 32, support wall 33, and side wall 36.

[0059] According to the sensor module 100 of this embodiment, a ring-shaped seal 15 is arranged at the boundary between the second peripheral wall 10a of the housing 10 and the first peripheral wall 3d of the fixing portion 3b of the cap 3, so that even if the sensor module 100 is placed outdoors, the first space 11 remains watertight and rainwater does not enter the first space 11.

[0060] According to the sensor module 100 of this embodiment, the remaining amount of kerosene 5 can be known at a location away from the fuel tank 1 without visually checking the inside of the fuel tank 1 or the like.

[0061] The sensor module 100 of this embodiment uses millimeter waves as radio waves, allowing them to penetrate resin. Therefore, even if the sensor module 100 is placed outside a resin cap 3 of a fuel tank 1, it is possible to calculate the remaining amount of kerosene 5 in the fuel tank 1 through the cap 3. If the radio waves were light, such as infrared or visible light, the cap 3 would need to be partially or entirely made of transparent or translucent resin or have holes drilled in it in order for the radio waves to pass through. However, by using millimeter waves as radio waves, the cap 3 does not need to be made of a transparent or translucent material or have holes drilled. Instead, the cap 3 can be made of a colored insulating material that does not transmit light, as is the case with existing caps, and drilling holes does not compromise its watertightness. Transparent and translucent materials tend to lose their transparency over time, resulting in degradation of their transmittance. If the cap 3 is made of metal, by replacing it with a plastic cap 3 sold exclusively by the manufacturer of the fuel tank 1, it becomes possible to calculate the remaining amount of kerosene 5 in the fuel tank 1 through the cap 3, and therefore the reliability of the safety of the state in which the cap 3 is attached to the opening 2 is guaranteed by the manufacturer of the fuel tank 1. Therefore, the reliability of the existing function of the fuel tank 1 is not impaired.

[0062] Other Embodiments (1) In the above embodiment, the support wall 33 and the side wall 36 of the sensor module 100 are cylindrical, but this is not limited thereto. Any curved or linear wall may be formed around the lens portion 32, and the wall may be a single wall or a structure in which multiple curved and / or linear walls are connected. Furthermore, the cylindrical side wall 36 may be formed in double or triple layers around the lens portion 32. The side wall 36 may be configured in any shape and in any number as long as it can reduce side lobes that adversely affect the reflected waves of radio waves reflected by the liquid surface 5 a of the kerosene 5.

[0063] (2) In the above embodiment, the side wall 36 of the sensor module 100 is made of resin and is integrally formed with the cap 3. However, the side wall 36 may be made of a material other than resin, such as metal. The side wall 36 may be made of any material as long as it can reduce side lobes that adversely affect the reflected waves of radio waves reflected by the liquid surface 5 a of the kerosene 5. In this case, for example, if the side wall 36 is made of metal, the metal side wall 36 can be joined to the cap 3 by insert molding at the same time as the resin molding of the cap 3.

[0064] (3) In the above embodiment, the sidewall 36 is configured so that the protruding end 36a contacts or is located near the first substrate 40. As a result, when viewed in the radial direction, the sidewall 36 almost completely overlaps the transceiver IC 21. However, this configuration is not limited to this. The sidewall 36 may be configured to have a height such that the protruding end 36a is spaced apart from the first substrate 40. In this case, the sidewall 36 may be configured to have a height such that at least a portion of the transceiver IC 21 overlaps the sidewall 36 when viewed in the radial direction, or such that the sidewall 36 does not overlap the transceiver IC 21 at all. In other words, at least a portion of the transceiver IC 21 may be located in the radially inner space 36b of the sidewall 36, or the transceiver IC 21 may not be located in the radially inner space 36b of the sidewall 36. The sidewall 36 may have any height as long as it can reduce side lobes that adversely affect the reflected waves of radio waves reflected by the liquid surface 5a of the kerosene 5.

[0065] (4) In the above embodiment, the side wall 36 of the sensor module 100 is erected from the bottom wall 31 of the cap 3 toward the transceiver IC 21, but this is not limited to this. Instead of or in addition to the side wall 36 extending from the bottom wall 31 toward the transceiver IC 21, the side wall 36 may extend from the bottom wall 31 in the opposite direction to the transceiver IC 21, i.e., toward the internal space 1a of the fuel tank 1. The side wall 36 may be located anywhere as long as it can reduce side lobes that adversely affect the radio waves reflected by the liquid surface 5a of the kerosene 5.

[0066] (5) In the above embodiment, the side wall 36 is disposed between the lens portion 32 and the support wall 33, but this is not limited to this. The side wall 36 may be disposed radially outward of the support wall 33. Even in this case, it is preferable that the side wall 36 be erected around the lens portion 32 in the same direction as the support wall 33.

[0067] (6) In the above embodiment, the resin material of the cap 3 is not specified. However, it may be, for example, a PBT (Poly Butylene Terephthalate) resin containing glass filler. By using a resin material containing glass filler, the cap 3 can be formed with high strength. Furthermore, for example, the resin material of the cap 3 may have a relative dielectric constant of 3 or more. By using a resin material with a relative dielectric constant of 3 or more for the cap 3 including the side wall 36, it is possible to reduce side lobes that adversely affect the reflected waves of radio waves reflected by the liquid surface 5a of the kerosene 5.

[0068] (7) In the above embodiment, the transmission / reception IC 21 and the calculation IC 22 are mounted on the first board 40, and the external communication IC 90 is mounted on the second board 50, but each IC can be mounted on any board.

[0069] (8) In the above embodiment, the sensor assembly 70 is composed of the first substrate 40 and the second substrate 50, but it may be composed of one substrate or three or more substrates.

[0070] (9) In the above embodiments, the sensor module 100 is configured to operate using the battery 62a. However, it may be configured to operate using a commercial power source.

[0071] (10) In the above embodiment, after the remaining amount of kerosene 5 falls below 50%, the remaining amount of kerosene 5 is transmitted by wireless signal every 10 minutes. However, this is not limited to this. For example, after the remaining amount of kerosene 5 falls below 50%, a wireless signal may be transmitted every time the remaining amount reaches 40%, 30%, and 20%, i.e., every time the kerosene 5 decreases by 10%. Furthermore, after the remaining amount of kerosene 5 falls below 20%, a wireless signal may be transmitted every time the kerosene 5 decreases by, for example, 3%. In this way, by increasing the frequency of wireless signal transmission as the fuel tank 1 approaches empty, it is possible to also serve as an alert that the fuel tank 1 is running empty.

[0072] The present disclosure can be used in a sensor module.

[0073] 1: Fuel tank (container) 1a: Internal space 2: Opening 3: Cap 3a: Lid portion 5: Kerosene (content) 10: Housing 11: First space (closed space) 20: Sensor portion 21: Transmitting / receiving IC (transmitting / receiving portion) 21a: Transmitting portion 21b: Receiving portion 22: Calculating IC (calculating portion) 32: Lens portion 33: Support wall 36: Side wall 60: Power supply portion 90: External communication IC (external communication portion) 100: Sensor module

Claims

1. A sensor module attached to an opening of a container in which an item is stored, comprising a cap and a sensor unit, wherein the cap has a lid portion closing the opening, a lens portion, a support wall arranged upright around the lens portion to support the sensor portion, and a side wall, wherein the sensor portion has a transceiver portion including a transmitter portion that transmits radio waves and a receiver portion that receives the radio waves, wherein the lens portion is arranged to face the transceiver portion of the sensor portion, wherein the transmitter portion transmits the radio waves which pass through the lens portion and reach the internal space of the container, and wherein the receiver portion receives the reflected waves after the radio waves are reflected by the item in the internal space, and wherein the side wall is arranged upright around the lens portion in the same direction as the support wall.

2. A sensor module as described in claim 1, wherein the sensor unit further has a calculation unit which calculates the remaining amount of the contained item or information for calculating the remaining amount based on the time from when the radio waves are transmitted from the transmitting unit to when the reflected waves are received by the receiving unit.

3. A sensor module as described in claim 2, further comprising an external communication unit which wirelessly transmits to the outside a signal indicating the remaining amount of the contained item calculated by the calculation unit or information for calculating the remaining amount.

4. The sensor module according to claim 3, further comprising a power supply unit, the power supply unit supplying power to the sensor unit and the external communication unit.

5. A sensor module as described in any one of claims 1 to 4, further comprising a housing configured to be freely attached and detached from the cap, wherein the sensor unit is housed in a closed space formed by the cap and the housing.

6. A sensor module according to any one of claims 1 to 4, wherein the side wall is formed integrally with the lid portion.

7. The sensor module according to any one of claims 1 to 4, wherein the side wall is cylindrical.

8. A sensor module according to any one of claims 1 to 4, wherein the radio waves transmitted from the transmitting unit are millimeter waves.

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